In .Net7 Web API doesn't return multipart content

I have tried to send file through multipart form content. The code in API like shown below:

app.MapGet("/GetFile", () =>
               {
                   MultipartFormDataContent multiPartContent = new MultipartFormDataContent("----MyGreatBoundary");
                   multiPartContent.Headers.ContentType = MediaTypeHeaderValue.Parse("multipart/form-data; boundary=----MyGreatBoundary");

                   HttpContent content1 = new ByteArrayContent(File.ReadAllBytes(@"C:/temp/TimeAkis.txt"));
                   content1.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("TimeAkis");
                   
                   content1.Headers.ContentDisposition.FileName = "TimeAkis.txt";
                   multiPartContent.Add(content1);

                   return multiPartContent;
               });

While accessing the above api method through a console application. We couldn't get the 'MultiPartContent'.

The code shown like below:

internal async Task Read()
{

HttpClient httpClient = new HttpClient();
            
            Uri webService = new Uri(@"https://localhost:44324/GetFile");
            HttpRequestMessage requestMessage = new HttpRequestMessage(HttpMethod.Get, webService);
            requestMessage.Headers.ExpectContinue = false;

            Task<HttpResponseMessage> httpRequest = httpClient.GetAsync(webService);
            HttpResponseMessage responseMessage = httpRequest.GetAwaiter().GetResult();

            string strContentType = responseMessage.Content.Headers.ContentType?.MediaType;
            if(strContentType != null && IsMultipartContentType(strContentType))
            {
                try
                {
                    var multipartcontent = await responseMessage.Content.ReadAsMultipartAsync();
                    foreach(HttpContent content in multipartcontent.Contents)
                    {

                    }
                }
                catch(Exception e)
                {
                    Console.WriteLine(e);
                    
                }
        }

}

It returns the content type as 'Json':

Please help us to get the multipart data. (OR)

Am I wrong in creating API with multipart?.

Please suggest to me.

Thanks.